How can I release an IP in Ubuntu Linux using command line options?
You need to simply type the following command. First, explicitly releases the current lease, and once the lease has been released, get the new IP:
sudo dhclient -r sudo dhclient
Open a command-line terminal (select Applications > Accessories > Terminal), and then type:
sudo dhclient -r sudo dhclient eth0
The above will release the eth0 interface IP and assigned it again. For a wireless interface called wlan0, try:
sudo dhclient -r sudo dhclient wlan0